The present invention relates in general to turbocharger systems for motor vehicles with internal combustion engines, and, more specifically, to air ducts for moving pressurized air between separate components within a turbocharged system.
Turbo systems can increase the power derived from an internal combustion engine by compressing the intake air provided to the engine. Turbochargers require ducting to move air from a compressor to a charge air cooler, and then to a throttle body on the engine. Elastomeric duct sections are typically used in order to provide easy installation, to accommodate variable alignment/distances between the components being joined, and to handle engine vibration or roll during vehicle operation.
The elastomeric duct sections typically experience internal air pressures of up to 3.5 bar, for example. Moreover, the ducts are typically exposed to high temperatures. The high temperatures and pressures may cause an air duct or hose to expand during turbocharger operation. Such a change in shape could have several drawbacks. The inflation of the duct outside diameter can cause interference with surrounding components, potentially resulting in abrasion of the duct surface, breaking of mounting brackets, burst hoses (resulting in lack of power), or slow leaks with a resulting hissing noise. In addition, a unrestrained pressurized duct surface can result in radiated sound from the turbocharger that reaches the passenger compartment, causing unacceptable noise disturbances to the passengers.
To address the foregoing issues, some kind of duct reinforcement is typically provided. One known approach has been to provide a metal helix (i.e., a slinky-shaped body) around the duct and then covering the duct and helix with a heat shrink polymeric sock. This results in a greatly increased manufacturing cost, as well as a greater difficulty of installation due to a higher stiffness.
Another approach has been to use composite, multi-layered charge air ducts with reinforcing plies and specialized polymers. Such composite ducts suffer the same drawbacks, such as increased manufacturing costs and environmental issues.